The invention relates to an apparatus for applying fluent material such as optionally foamable substances of differing viscosity, coating substances, varnishes, adhesives, pastes, etc. to a substrate, such as a web of material with at least one pressing part in the length of the apparatus (application width) for engaging in a substrate path and with a pressing device for operating the pressing part. Such an application apparatus is used in machines for flat stencil printing, round stencil applications and/or devices for stencil-free, full-surface applications, in which the application width or extension of the pressing part can be several meters. As a function of the sphere of use it is possible to make patterning applications (printing) and/or full-surface applications (e.g. impregnation, coating, dyeing and varnishing).
Conventional solid doctor or squeegee strips (pressing parts) with a length of several meters, due to the necessary inherent rigidity, have a considerable curvature over the application width, which is prejudicial to the desired straightness of a doctor strip for engaging on a substrate, such as a material web. Mechanical pressing of such a doctor strip requires complicated doctor mounting supports with which pressing forces are exerted on the ends of the doctor strip, which leads to considerable mechanical expenditure and very solid and robust mounting supports. In addition, the fixing of the doctor strip between the mounting supports leads to an undesired sag over the application width which, like the curvature as a result of inherent stability, can only be counteracted by strengthening the mechanical, lateral pressing. It is also known to magnetically press against a magnetic beam or bar arranged below the material web solid, magnetizable material strips and coating or roll doctors. Either a steel doctor or squeegee device is pressed against the material web (DE-AS 1 135 856) or a magnetizable bar is placed on the back of a sheet or blade-like spreading doctor and presses the latter against the material web (Swiss patent 571 952, DE-OS 34 19 590). The main disadvantages of the known magnetic doctor pressing devices are the dependence of the pressing force on the magnetizable mass or the cross-section of the doctor strip and the distance between the magnetic force-producing and magnetizable means. The doctor must be made for magnetizable material, or must be connected to a longitudinally extending, magnetizable material strip. The bending or curvature of such doctor strips due to inherent rigidity is relatively large not only in use, but at the time of manufacture. Rolled or drawn steel profiles are characterized by strong tensional forces, which are released by machining and/or stressing and lead to a considerable curvature of the profile, which is unsuitable for a linear doctor pressing over several meters. Therefore solid doctors or squeegee devices with complicated mounting supports for mechanical pressing can scarcely be replaced by magnetizable coating profiles pressable by a magnetic force, apart from the use of magnetically pressable squeegee devices in textile stencil printing, but which use has been restricted to relatively small application widths and relatively small magnetizing masses of the squeegee device.